<div>
  This field works in conjunction with the proxy server field
  to specify the username used to authenticate with the proxy.

  <p>
  If this proxy requires Microsofts <a href="https://en.wikipedia.org/wiki/NTLM">NTLM</a>
  authentication scheme then the domain name can be encoded
  within the username by prefixing the domain name followed
  by a back-slash '\' before the username, e.g "ACME\John Doo".
</div>
